Optical pickup-use object lens, optical pickup and optical...

Details Optical pickup-use object lens, optical pickup and optical... Optical pickup-use object lens, optical pickup and optical...

2006-05-23

2006-05-23

Nguyen, Hoa T. (Department: 2656)

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

C369S112260

Reexamination Certificate

active

07050379

ABSTRACT:
The present invention is relative to an objective lens (15) for an optical pickup, having a numerical aperture not less than 0.8, and adapted for correcting the chromatic aberration at an image point on an optical axis for light with a wavelength within several nm about a reference wavelength which is not larger than 420 nm. This objective lens is made up by a first lens set GR1, having a compound surface S2of a refractive surface S2rand a diffractive surface S2d, and a second lens set GR2, having a positive refractive power, looking from the light source side. The compound surface of the first lens set is formed by adding the diffractive surface having the positive refractive power to the refractive surface which is an aspherical surface having the negative refractive power. The lens forming the second lens set is a single lens including at least one aspherical lens. This objective lens is small-sized, permits effective correction of chromatic aberration and enables the laser light to be converged to close to the diffraction threshold.

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International Preliminary Examination Report Apr. 30, 2003.
International Search Report Jun. 4, 2002.

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